In recent years, to improve performance in various types of device systems, for example, for improvement of brake control in vehicles or improvement of fuel efficiency in hybrid systems, electrical component to be used in device systems have been advanced toward further diversification and more varieties of product models, so that circuit diagrams of device systems have been complicated. Various techniques have been proposed for presenting connection condition among electrical component contained in such complicated device system circuit diagrams, as well as methods for divisionally transmitting various types of data via networks have also been proposed.
For example, various types of device systems in vehicles vary depending on vehicle types, vehicle grades and the like and have been being improved day by day. Vehicle maintenance departments or maintenance contract companies are required to check wiring statuses among electrical component in maintenance and inspection of those systems. On such occasions, circuit diagrams in which systems' design circuits are rewritten with interconnecting lines and various types of connectors for connection of interconnecting lines to electrical component are used. However, those rewritten circuit diagrams are also complicated naturally due to complications of the systems and increases in electrical component counts as described above, and system improvements involve latest and older circuit diagrams. Therefore, for vehicle maintenance departments and maintenance contract companies, it would be impracticable to accumulate circuit diagrams for all device systems, and there have been proposed methods relying on supply of necessary circuit diagram data from a server each time it is required. Even if a data dividing-and-transmitting method is used for such data transmission, circuit diagrams are not displayed until data received by the divisional transmission is restructured on the receiver side. Standby time required until circuit diagrams obtained through data divisional transmission and data restructuring are displayed becomes increasingly longer as the communication frequency band of a data communications network that provides data transmission with the server becomes narrower. Due to this, in an environment in which broadband data communications cannot be expected or under a condition of a low processing speed for data restructuring by a apparatus on the divisional-transmission reception side, the wait time is elongated such that the user may feel a sense of incompatibility as if a system abnormality occurred. Such an incompatible feeling would last increasingly longer with increasing amount of circuit diagram data to be transmitted, or the incompatible feeling becomes increasingly more noticeable with decreasing processing speed of data restructuring, hence a desire for improvement of the case. In addition, it is also desirable to provide circuit diagram ready for improvement of equipment systems as well as to accomplish improvement of generality and cost reduction involved. Although vehicles are described as an example, the case is similar also with ships and aircraft, machine tools, plant facilities, and the like.